How do you know it is over wound?
Nest if is you need to letthe spring go and see if it will go.There is a tool to do this with.Then take out the spring to see if it broken.
As far as it not ticking then this could do with the overwound spring and requires a ne one.
If it is not broken then rewinfd it carefully and then se if you can clean the rest of the clock movement and oil.
Once done get it into beat(a nice tick and tock).
Ray
November 2010